1. Field of the Invention
This invention generally relates to an electric, automatic mixing drink dispenser for mixing liquid drink concentrate with water to make a mixed drink on demand and methods of mixing and dispensing drinks with such a mixing drink dispenser
2. Discussion of the Prior Art
Electrical, commercial mixing drink dispensers of type that mix liquid drink concentrate with carbonated or noncarbonated mixing water on demand to make and dispense a mixed drink are well known, but suffer from a number of disadvantages. When a manual switch is actuated, mixing water and drink concentrate from a concentrate hopper are injected into a mixing chamber where they are mixed together to make a mixed beverage and then dispensed. In some cases, actuation of the start switch starts a timer that fixes a preselected total quantity of mixed drink to be dispensed. In other dispensers, the mixing and dispensing proceeds continuously as long as a dispense switch is manually held in an actuated state.
In some cases, the mixing is achieved with rotating mixing blades that disadvantageously become dirty and need to be cleaned periodically or become worn and need replacement. In some cases, a drain valve, subject to wear and clogging may be used to block dispensing of the beverage from the mixing chamber until for a preselected time period until fully mixed. The concentrate is generally maintained within a concentrate hopper with a drain hole, while the mixing water is generally obtained from a public source of pressurized water from a faucet. Both the mixing water and the concentrate are fed to a proportional valve to maintain a preselected ratio of concentrate to mixing water over the mixing of the many mixed drinks that are made from the a single hopper load of concentrate. Again, such proportionate valves are expensive and require periodic cleaning and maintenance if the concentrate to mixing water is to be maintained. Other computer controlled valves based on mixing water quantity measurements and concentrate quantity measurement may also be used, but the need for a valve for each of the concentrate and water is still required as well as the higher cost of a computer and associated interfaces.
In mixing drink dispensers that rely upon the measured length of time that a concentrate outlet valve is open to determine the quantity of concentrate that is dispensed to the mixing chamber, a problem exists with respect to maintaining the rate of concentrate dispensing because of the lowering of the concentrate head pressure at the concentrate hopper drain hole as the concentrate in the hopper is gradually depleted and the level becomes lower. As the level of the concentrate in the hopper becomes lower, the head pressure forcing the concentrate out of the drain hole becomes less and the rate of concentrate flow gradually decreases. Such change in concentrate flow rates disadvantageously results in a non-uniform drink product which may be too strong when the concentrate hopper is first filled and is too weak when the concentrate hopper is nearly depleted.
The inventor has also noted that the concentrates fail to maintain a uniform density throughout the normal periods of storage within the concentrate hopper between concentrate refills. Consequently, even if the same fluid volume per drink is maintained over the plurality of drinks that are made, the uniformity of flavor intensity varies. Over time, the heavier elements of the concentrate gradually settle toward the bottom. Accordingly, after a period of time, the first drinks are made with a more highly concentrated concentrate than the drinks that are made later.
Another problem noted by the inventor with existing mixing drink dispensers is that in some cases the same concentrate may be stored within the drink dispenser over a substantial length of time. Even with cooling of concentrate, this long term storage of the concentrate exposed to the oxygen in the air causes gradual deterioration of the taste, smell and other flavor elements of the concentrate and eventually spoilage due to mold and aerobic bacteria.